The human scalp normally harbors 100,000 to 150,000 hair follicles or hairs. The hair follicles or hair roots are the hair-forming organs. The long, strong, hairs, which build up the hair coverage of the head, are referred to as terminal hairs. The very fine, very short hairs, barely protruding over the surface of the skin, at the edges of the hair coverage on the head are referred to as fuzz hair, or vellus hair.
The growth of hair is not continuous, but cyclical. Three growth phases are identified: (1) the anagen phase, (2) the catagen phase, and (3) the telogen phase. The anagen phase is the period of active hair growth and, insofar as scalp hair is concerned, generally lasts from 3-5 years. The catagen phase is a short transitional phase between the anagen and the telogen phases, which, in the case of scalp hair, lasts only 1-2 weeks. The telogen phase is essentially a quiescent or resting phase where all growth ceases and the hair eventually is shed prior to the commencement of a new growth cycle. Scalp hair in the telogen phase is also relatively short-lived, some 3-4 months elapsing before the hair is shed and a new hair begins to grow. The hair of the head is thus under constant renewal. At any given time approximately 88% of the hairs are in the anagen phase, 1% are in the catagen phase, and the remainder are in the telogen phase.
Dermatologists recognize many different types of hair loss, the most common by far being “alopecia,” or male pattern baldness, in which humans, typically males, begin losing scalp hair at the temples and on the crown of the head as they get older. While this kind of hair loss is largely confined to males, it is not unknown in women. Other types of hair loss, which can be considerable, temporary or permanent, can be induced by poor nutrition; emotional stress; hormone imbalance; or medicinal drugs, such as cancer chemotherapy agents. These disorders and the mechanisms that produce them are poorly understood. Nevertheless, they are common and distressing, since hair is an important factor in human social and sexual communication.
U.S. Pat. No. 4,596,812 to Chidsey III et al. discloses a method for treating alopecia which comprises regular topical application of the compound 2,4-diamino-6-piperidino-pyrimidine 3-oxide or “Minoxidil.”
U.S. Pat. No. 5,523,078 to Baylin discloses an aqueous composition for the treatment of hair and scalp which includes a chelating agent, gellan gum, a vitamin precursor, a preservative, biotin, a vitamin derivative, gamma-linolenic acid, menthol, a liposome, a conditioner, a solubilizer, a conditioner/humectant, folic acid, and a poly amino sugar condensate.
U.S. Pat. No. 6,465,514 to Hallam discloses compositions consisting essentially of procaine hydrochloride, niacin and minoxidil. The compositions are allegedly useful for promoting hair growth.
U.S. Pat. No. 6,511,659 to Mahe et al. discloses pyrimidine 3-oxide compounds allegedly useful for inducing/stimulating hair growth or retarding hair loss.
U.S. Pat. No. 6,271,246 to Murad discloses pharmaceutical compositions consisting essentially of an acidic component comprising a hydroxy acid or tannic acid, a niacin component, and a 5-α reductase inhibitor. The compositions are useful for managing scalp conditions such as thinning hair.
U.S. Pat. No. 5,804,594 to Murad discloses pharmaceutical compositions useful for improving wrinkles and other skin conditions. The compositions include a sugar compound that is converted to glycosaminoglycan in the patient, a primary antioxidant component, at least one amino acid component, and at least one transition metal component.
Despite attempts in the pharmaceutical and cosmetic industry to develop compositions to promote hair growth and reduce alopecia, no widely accepted solution exists. Moreover, many of the proposed solutions present unwanted side effects. Hence, there is still a need for effective and safe compositions to promote hair growth.